Manufacture of zinc oxide



Patented Oct. 2l, 1924K.

UNITED STATESl GEORGE S. BROOKS, 0F GARY, INDIANA.

MANUFAGTURE 0F ZINC OXIDE.

Application led February 27, 1922. Serial No. 539,460.

To all whom it may concer/n.'

Be it known that I, GEORGE S. BROOKS, a citizen of the United States, residing at Gary, inthe county of Lake and State of Indiana, have invented a new and useful Improvement in the Manufacture of Zinc Oxide, of which the 'following a specification'.-v

The present invention relates to the manufact-ure of zinc oxide by the retort volatilizing, or French process and will be fully understood from the following description, il lustrated b the accompanying drawing, in Which a .orm of apparatus suitable for carrying out the invention is illustrated, in part diagrammatically In the manufacture of zinc oxide in aceordance with the present invention, the usual form of retorts 'may be used, the mouths of which open into flues or passages in 4which a current of air is present, and wherein oxidation of the vapors of the zinc takes place. During the volatilization of the zinc, the volume of the zinc in the re tort is completely or partially replenished by feeding fresh zinc into-the retort, either from time to time or continuously at a rate not greater than the rate of volatilization of the zinc. In accordance with the present invention, it has been found desirable to employ for replenishment a spelter or metal containing not more than 0.07% of lead, the metal employed being preferably of the character of that obtained by electrodepoB sition from solutions of zinc salts derived directl from suitable zinc ores. The use of spe ter of thls character materially 1n- Vcreases the length of runs and improves the character of the zinc oxide formed, permittin of full control of the latter.

he zinc metal to be retorted is preferably pre-formed in sheets or plates, say, of to 1/4 inch thickness, in any suitable manner, for example, bty electro-deposition from solutions derived rom the lixiviation of suitable zinc ores. The zinc thus de posited is low in impurities, containing less than 0.07% lead.

The initiall formed zinc plate is mechanically reduce to strip or sticks oi a suitable size for introduction into the volatilizing retort, this bein accomplished by means of any suitable device such as a mechanical shears.

The metal, in strip or stick form, is fed in at the mouth of the retort, from which the zinc vapors are evolved and where the' l oxidation into oxide of zinc is effected. The

in-fed metal is retained at or near the mouth of the retort in. the heating zone created by the oxidation of the vaporized zinc, or by its superheat in case no oxidation is taking place, as for example, in the refining of zinc metal by retort volatilization. or strips of zinc may suitably be inserted into the retort from time to time, as the amount of zinc volatilized therefrom equals or exceeds the zinc of the strip or stick. In such case the strip may suitably be held in the heated zone outside the mouth of the retort prior to its introduction until it is brought to as high a temperature as possible, preferably just below its melting point. 'When so heated, it is inserted through the mouth of the retort and added to the molten metal for the replenishment of the latter. Cooling of the retort and the resulting in- The sticks i jury to its material is thereby minimized 'and the regularity of the operation of the plastic and, as it enters the retort, bending downward of its own weight to meet the level of the molten zinc in the retort. By such continuous feed of the zinc mea-l, a continuous and regular operation of the retort may be maintained, particularly when using a meta-l of the character above described containing not more than 0.07% of lead.

In the drawings, apparatus is shown which may suitably be used for the con tinuous feeding', for example, of strips into the volatilizing furnace.v

Figure l is a sectional view through the retort, showing the feeding mechanism in plan;

Fig. 2 is a sectional View on the line 2-2 of Fig. 1, and

Fig. 3 is a detail sectional view through the feeding nozzle on a slightly enlarged scale.

In the drawings, the numeral 5 indicates a retort `Ier'oyided Yat `its mouth lWith ya dam 7 and `In',Ollllliivl iin suitable furnace setting 8. The mouth of the retort opens into a suitable flue or conduit 9 through Which air may be drawn in the manufacture of theoxide, combining with the zinc vapors issuing from the mouth of the retortand' forming zinc oxide, Which passes upwardly through the conduit or flue'into suitable settling chambers or bag houses (not shown). Op 'osite .themouth `of the retort {6-a WatercoolJed,` nozzle 1 0 protrudes into the tlue19, the nozzle opening fbeing of a Width and thickness'suitableifor passa e through it, forexample, of Va mechanica-l y cut strip of spelter Afrom `an electrolytically deposited plate of, say, about 1/8 of an inch thiclmess. The nozzle forms-theend of suitable feedingmechanism mounted upon a Wheeled carriage 11 suspended from a trolley, which may suitably be an I-beam 12. The feeding mechanism illustrated consists of a` frame 13 `upon which are mounted feeding rollers 1lihrendy idle rolls 15 for feeding and` guiding the strips to and through the nozzle.v Any suitable driving mechanism retort, yas :shown at may be employed. for the feedrolls 1.4. The A,end lofthe nozzle 1 is at a point outside the-mouth'of-y the retort 6 at Which the full heatingej'ectofthe zinc oxide-flame issuing vfrom the mouth of the. retort is felt. The zinc strips are slowly fed through the zinc oxide `flame, -the rate being so controlled that they approach their melting point, becoming very plastic andbending ldownward to nieet-thefsurface ofthe molten zinc in the 1. In'the process of producing zinc oxide by volftilizmg zinc metal in a retort and oxidizingithe volatilized ,zinc upon leaving the retort, the improvement which consists in feeding solid; zinc. metal into the retort during the volatilization through the heating zone-formed bythe-oxidizing name, the in-fedzinc being subjected tothe heating action of the flame for a fsucieant i Y' to effect f a substantial heatingitliereo? 2. In the process of producing zinc oxide by volatilizin zinc metal in a retort and oxidizing the voatilized zinc upon leaving the reto-rt, the improvement which consists in feeding solid zinc metal into the retort during the volatilization through the heating r/one formed by the oxidizing flame, the in-fed zinc being subjected to the heating action `of the flame for a suiiicient periodof time to :bring it substantially to the melting' point of the zinc.` 4 i 3. In the process of producing zinc oxide by volatili'zing zinc metal in a retort and oxidizing the volatilized zinc upon leaving the retort, the improvement which consists, in continuouslv feeding solid zinc metal into the retort during the vola-tilization through the heating zonev formed by the oxidizing iiame, the rate of feed of the in-fedrzjinc ing such that the zinc metal is broughtl substantially to its melting point upon entering the retort.

4. In the retort volatilization of; zinc, maintaining a substantial body Aof'molten zinc in a volatilizing retortand continuously feeding solidzinc into the retort at a rate to substantially replace zinc vola-- tilized therefrom. 4

5. In the retort volatilization of zinc, maintaining a substantial body of molten zinc in a. volatilizing retort and continuously feeding solid .zinc into thev retort through the vapors issuing therefrom at a rate to substantially replace thezinc volatilized therefrom, the in-fedl zincvbeing thereby preheated. v

6. In the retort volatilization of zinc, maintaining a substantial body of lmolten zinc in a volatilizing retort, feeding solid, 

